CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $)	3 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (7,664,000)	$ (8,092,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	662,000	884,000
Depreciation and amortization	260,000	203,000
Amortization of discount on notes payable and debt issuance costs	0	21,000
Changes in operating assets and liabilities:
Trade and other receivables, net	82,000	302,000
Government contract receivables	0	93,000
Inventories, net	(2,133,000)	803,000
Prepaid expenses and other current assets, net	(92,000)	108,000
Other non-current assets	0	98,000
Accounts payable	621,000	(1,159,000)
Accrued clinical trial site and related fees	(202,000)	494,000
Accrued payroll and related expenses	440,000	77,000
Deferred revenue	2,328,000	(1,550,000)
Customer deposits	5,359,000	(1,470,000)
Other current liabilities	275,000	83,000
Other long-term liabilities	(37,000)	(166,000)
Net cash used in operating activities	(101,000)	(9,271,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property acquisitions	(190,000)	(363,000)
(Increase) decrease in other assets	(175,000)	31,000
Net cash used in investing activities	(365,000)	(332,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock, net of issuance costs of $59,000 and $126,000, respectively	1,443,000	3,587,000
Principal payments on notes payable and capital leases	(19,000)	(519,000)
Net cash provided by financing activities	1,424,000	3,068,000
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	958,000	(6,535,000)
CASH AND CASH EQUIVALENTS, beginning of period	18,033,000	23,075,000
CASH AND CASH EQUIVALENTS, end of period	18,991,000	16,540,000
SCHEDULE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Accounts payable for purchase of property	$ 38,000	$ 72,000